Various types of systems and devices (e.g., flatbed scanners and inkjet printers) include a scanning device having a cable provided to a movable body and configured to reciprocate between a first structural member and a second structural member. In a flatbed scanner, for instance, a casing functions as the first structural member, a platen glass functions as the second structural member, and a carriage equipped with an image sensor functions as the movable body. The carriage is configured to reciprocate the image sensor along the platen glass (i.e., move the image sensor back and forth along the platen glass). In the example of an inkjet printer, a guide rail functions as the first structural member, a cover functions as the second structural member, and a carriage equipped with a recording head functions as the movable body. The carriage is configured to reciprocate the recording head along the guide rail.
FIG. 16 shows an internal structure of a flatbed scanner 100 including a known scanning device. The flatbed scanner 100 includes a casing 101 and a platen glass 102, which form a housing of the flatbed scanner 100. In particular, the platen glass 102 forms at least a part of a top of the housing. The flatbed scanner 100 may further include a carriage 103 in an internal space of the housing. The carriage 103 is configured to reciprocate along a guide shaft 104 that is disposed such that its axis extends in parallel to the platen glass 102. A drive mechanism (not shown) for reciprocating the carriage 103 may also be included in flatbed scanner 100.
The carriage 103 is equipped with an image sensor 105, which may include, for example, a contact image sensor (CIS). The image sensor 105 irradiates the platen glass 102 with light such that at least a portion of the light passes through platen glass 102 and hits a document or material to be scanned. The image sensor 105 may further detect an intensity of light reflected from the document placed on the platen glass 102. The image sensor 105 then outputs an electrical signal in accordance with the intensity of the reflected light. The image sensor 105 is connected with an electrical cable 106 configured to output an electrical signal and to supply power to a light source. The electrical cable 106 is connected at one end to the image sensor 105 and is fixed at its other end by a fixing portion 107 provided at a bottom of the casing 101. The electrical cable 106 is drawn to the outside of the casing 101 through the fixing portion 107 so as to extend to a control board. The electrical cable 106 is electrically connected to the control board.
The electrical cable 106 is routed so as to make a U-turn (a curved portion 108) at a portion thereof extending between the image sensor 105 and the fixing portion 107 such that the curved portion 108 has a substantially U-shaped configuration. As the carriage 103 reciprocates along the platen glass 102, the image sensor 105 reciprocates together with the carriage 103. At that time, the electrical cable 106 follows the reciprocating movement of the image sensor 105 causing the shape and position of the curved portion 108 of the electrical cable 106 to change. In FIG. 16, the various positions and shapes of electrical cable 106 as it follows the image sensor 105 is illustrated by double dotted lines.
The electrical cable 106 generally includes wires as conductors and a resin for insulating the conductors. When a plurality of wires are used to form the electrical cable 106, the wires are placed so as to run parallel to each other and are insulated with a resin so as to form a single member. In such a configuration, the wide electrical cable 106 is often referred to as a flat or ribbon cable. Further, because the wires and the resin both have flexibility, the electrical cable 106 is a flexible flat cable. While a bending strength of electrical cable 106 may vary depending on a size of the wires and a thickness of the resin, the bending strength of the electrical cable 106 generally corresponds to an allowable range to follow the reciprocating movement of the image sensor 105.
As shown in FIG. 16, in the electrical cable 106 that follows the reciprocating movement of the image sensor 105, a diameter of the curved portion 108 changes in accordance with the position of image sensor 105. When the curved portion 108 of the electrical cable 106 is located at a position near the image sensor 105, for example, the diameter of the curved portion 108 is relatively small. As a distance between the curved portion 108 of the electrical cable 106 and the image sensor 105 becomes greater, the diameter of the curved portion 108 becomes relatively larger. As indicated by the double dotted line in FIG. 16, depending on the bending strength of the electrical cable 106, the curved portion 108 of the electrical cable 106 may try to extend beyond a distance between the casing 101 and the platen glass 102. In this case, the electrical cable 106 makes contact with the platen glass 102 (i.e., platen glass 102 restricts expansion of curved portion 108).
If the image sensor 105 is moved leftward from a position shown in FIG. 16 while the electrical cable 106 is in contact with the platen glass 102, the curved portion 108 of the electrical cable 106 may not be smoothly moved due to frictional resistance caused by the contact between the curved portion 108 and the platen glass 102. As a result, the electrical cable 106 may buckle at a portion thereof indicated by an arrow 109 in FIG. 16. Such a problem may occur not only when the carriage 103 reciprocates to read an image by the image sensor 105 but also when the carriage 103 moves during transport of the flatbed scanner 100.